Generally we will use onchange event of Dropdownlist in asp.net to raise dropdownlist selectedindexchanged event in JavaScript like as shown below
<asp:DropDownList runat="server" ID="ddlID" onchange="JavaScript:
onSelectChange ();">
</asp:DropDownList>
</asp:DropDownList>
<script>
function onSelectChange()
{
alert("hello
!");
}
</script>
You can also add Javascript function on dropdownlist onchange event from code behind page
file as follows.Just add bellowcode on Page_Load Event of Page.
ddlID.Attributes.Add("onChange", "return
onSelectChange ();");
